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Patented J... 14, 1947.
21,414,119
lum'rso STATES PATENT OFFICE
v rnonnc'rron or VANILLIC ACID
.
A. Pearl, Appleton, Wis., assignor, by mesne
assignments, to Cola ,G. Parker, Neenah', Wis.,
_ astrustee
No Drawing. Application April 3, 1944,
Serial No. 529.425.
'1
6 Claims.
The present invention relates to the produc
tion of vanillic and closely related acids, and to
an improved process for producingacids derived
V by oxidation from vanillin, ortho-vanillin, and
syringaldehyde.
‘
Most aldehydes may be transformed to the
corresponding acids by common oxidizing agents
or' in the Cannizzaro reaction. vhut vanillin,
(Cl. 260-521)
original vanillin will remain unchanged and be
available as part of a new‘charge.
'
Without further elaboration the foregoing will
so fullyexplain the invention that others may
readily adapt the same for use under various
‘conditions of service.
I claim:
>
,
'
1. The cyclic method of producing vanillic
acid from vanillin, which comprises: adding one
> and have been reported as not amenable to either 10 mole of vanillin to a boiling-hot aqueous solution‘
ortho-vanillin, andsyrin'galdehyde' are exceptions
reaction. Ordinary oxidizing agents either (1)
have no action on the compound or (2) act as
dehydrogenating agents, and yield the dehy
drodicompound or (3) cause complete decom
position.»
I have discovered that vanillin can be trans->
' formed to a vanillic acid salt without the forma
tion of other undesirable products by treating it
in hot aqueous alkaline solution with mercuric
oxide. Expressed in terms of the net result, the
reaction would be as follows:
‘-
.
containing one mole of mercuric oxide and two
moles of sodium hydroxide; re?uxing for about
seven hours: acidifying with sulfur dioxide;
boiling for about ten minutes; ?ltering hot to
15 separate vanillic acid and unreacted vanillin in
the ?ltrate, from mercury in the'precipitate;
cooling to precipitate vanillic acid; returning the
vanillin remaining in the solution to the ?rst
step above recited; and returning the mercury “
in the precipitate, in the form of oxide, to the
?rst step above recited.
’
2. The cyclic method of producing. vanillic
acid from vanillin, which comprises: boiling
Subsequently, only acidi?cation isrequired to
secure the acid itself.
'
An example according to the invention is as
follows:
.
Example I
_
To a hot solution, at or near 100° 0., contain
vanillin in. an aqueous solution containing mer
25 curic oxide and sodium hydroxide; acidifying
with sulfur dioxide; boiling to‘ decompose corn-v
plex mercury compounds; ?ltering hot to sepa
rate vanillic‘aci‘d'and unreacted vanillin in the
?ltrate, from mercury in the precipitate; ‘cooling
30 to precipitate vanillic acid; returning the vanillin
remaining in the solution to the ?rst step above
' ing 2 moles, or 80 parts of sodium hydroxide and
one mole or 216 parts of mercuric oxide in about
1,000 parts of water add one mole or 152 parts
recited; and returning the mercury in the pre
cipitate, in the form of oxide, to the ?rst step
of vanillin with constant stirring. Continue the
boiling under a re?ux with stirring and when
the reaction is complete allow to cool. This may
3. The method ‘of producing vanillic acid
‘require from two to seven hours of boiling.
Acidify the cooled mass with sulfur dioxide, which
above recited.
V
'
from vanillin, which comprises; boiling vanillin
in "an aqueous solution containing mercuric oxide
‘and sodium hydroxide; acidifying with sulfur
dioxide; boiling to decompose complex mercury
will add a granular white precipitate to the solids 40 compounds; ?ltering hot to separate vanillic
already in the mass. Boil the mass, which will
acid and unreacted vanillin in the ?lterate, from
decompose the complex mercury compounds
mercury in the precipitate; and cooling to pre
present, and ?lter the. mixture hot to separate
cipitate vanillic acid.
'
both vanillin and vanillic acid in the ?ltrate.
4. The cyclic method of producing the de
The residue will contain all the mercury, which 45 rived monocarboxylic acid from an aromatic
can be returned to any suitable recovery‘opera- '
tion. Cool the ?ltrate to room temperature, 20°
‘0., and ?lter out the precipitated vanillic acid,
leaving unchanged vanillin in the ?ltrate. Neu
tralize the ?ltrate with sodium hydroxide and
then acidify with a strong mineral acid, which
will precipitate the unchanged vanillin, if de-
sired.
Alternatively the neutralized ?ltrate is
aldehyde- selected from vthe class comprising
vanillin, ortho-vanillln and syringaldehyde.
which comprises: adding one mole of the alde
hyde to a boiling hot aqueous solution contain
ing one mole of mercuric oxide and two moles
of sodium hydroxide; re?uxing. for about two
hours; acidifying with sulfur dioxide; boiling
for about ten minutes; ?ltering hot to separate
the monocarboxylic acid and unreacted aldehyde
conditions described above, about 30% of the 55 in the ?ltrate, from mercury in the precipitate;
ready to form part of a new charge. Under the
2,414,119
in the precipitate,~ in the form of oxide, to the
to the ?rst step above recited; and returning the
mercury in the precipitate, in the form of oxide,
to the ?rst step above recited.
6. The method of producing the derived
?rst step above recited.
monocarboxylic acid from an aromatic aldehyde
coolingto precipitate the acid; returning the
aldehyde remaining in the solution to the ?rst
, step above‘ recited; "and returning the mercury
’
‘
5. The cyclic method of producing the de
selected from the class comprising vanillin,
rived monocarboxyiic acid from an aromatic
aldehyde selected from the class comprising va
ortho-vanillin and syringaidehyde, which com~
prises: boiling the aldehyde in an aqueous solu
tion containing mercuric oxide and sodium hy
nillin, orthowaniliin and syringaldehyde. which
comprises: boiling the aldehyde in an aqueous 10 droxide; acidifying with sulfur dioxide; boiling
to decompose mercury compounds; ?ltering hot
solution containing mercuric oxide and sodium
to separate the monocarboxyiic acid and unre
hydroxide; acidifying with sulfur dioxide; boiling
acted aldehyde in the filtrate, from mercury in
to decompose mercury compounds; ?ltering hot
the precipitate; and cooling to precipitate the
to separate the monocarboxylic acid and unre
acted aldehyde in the ?ltrate, from mercury in 15 acid.
IRWIN A. PEARL.
the precipitate: cooling to precipitate the acid;
returning the aldehyde remaining in the solution
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